Hooded gunmen attacked a shop in the northeastern town of Wajir, about 100 km (60 miles) from the Somali border, firing guns and setting off explosions, witnesses said late on Tuesday.

"They locked (people) inside the shop, set it on fire and left. Three died inside while one (died) while being ferried to hospital," said Mohamed Siyat, a county government official.

The Islamist group Al Shabaab claimed responsibility for the raid. The militants last week also killed several people when they attacked a convoy carrying a regional Kenyan governor, Ali Roba, near the Mandera area bordering Somalia.

The northeastern region stretching from Wajir to the border town of Mandera has often been targeted by al Shabaab, which has vowed to punish Kenya for sending troops into Somalia where they are fighting alongside other African peacekeepers.